ALSA: rawmidi: Pass rawmidi directly to snd_rawmidi_kernel_open()

snd_rawmidi_kernel_open() is used only internally from ALSA sequencer,
so far, and parsing the card / device matching table at each open is
redundant, as each sequencer client already gets the rawmidi object
beforehand.

This patch optimizes the path by passing the rawmidi object directly
at snd_rawmidi_kernel_open().  This is also a preparation for the
upcoming UMP rawmidi I/O support.

Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230523075358.9672-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/rawmidi.h

@@ -161,7 +161,7 @@ int snd_rawmidi_proceed(struct snd_rawmidi_substream *substream);
 /* main midi functions */
 
 int snd_rawmidi_info_select(struct snd_card *card, struct snd_rawmidi_info *info);
-int snd_rawmidi_kernel_open(struct snd_card *card, int device, int subdevice,
+int snd_rawmidi_kernel_open(struct snd_rawmidi *rmidi, int subdevice,
 			    int mode, struct snd_rawmidi_file *rfile);
 int snd_rawmidi_kernel_release(struct snd_rawmidi_file *rfile);
 int snd_rawmidi_output_params(struct snd_rawmidi_substream *substream,

sound/core/rawmidi.c

@@ -406,24 +406,15 @@ static int rawmidi_open_priv(struct snd_rawmidi *rmidi, int subdevice, int mode,
 }
 
 /* called from sound/core/seq/seq_midi.c */
-int snd_rawmidi_kernel_open(struct snd_card *card, int device, int subdevice,
+int snd_rawmidi_kernel_open(struct snd_rawmidi *rmidi, int subdevice,
 			    int mode, struct snd_rawmidi_file *rfile)
 {
-	struct snd_rawmidi *rmidi;
-	int err = 0;
+	int err;
 
 	if (snd_BUG_ON(!rfile))
 		return -EINVAL;
-
-	mutex_lock(&register_mutex);
-	rmidi = snd_rawmidi_search(card, device);
-	if (!rmidi)
-		err = -ENODEV;
-	else if (!try_module_get(rmidi->card->module))
-		err = -ENXIO;
-	mutex_unlock(&register_mutex);
-	if (err < 0)
-		return err;
+	if (!try_module_get(rmidi->card->module))
+		return -ENXIO;
 
 	mutex_lock(&rmidi->open_mutex);
 	err = rawmidi_open_priv(rmidi, subdevice, mode, rfile);

sound/core/seq/seq_midi.c

@@ -38,6 +38,7 @@ MODULE_PARM_DESC(input_buffer_size, "Input buffer size in bytes.");
 /* data for this midi synth driver */
 struct seq_midisynth {
 	struct snd_card *card;
+	struct snd_rawmidi *rmidi;
 	int device;
 	int subdevice;
 	struct snd_rawmidi_file input_rfile;
@@ -168,8 +169,7 @@ static int midisynth_subscribe(void *private_data, struct snd_seq_port_subscribe
 	struct snd_rawmidi_params params;
 
 	/* open midi port */
-	err = snd_rawmidi_kernel_open(msynth->card, msynth->device,
-				      msynth->subdevice,
+	err = snd_rawmidi_kernel_open(msynth->rmidi, msynth->subdevice,
 				      SNDRV_RAWMIDI_LFLG_INPUT,
 				      &msynth->input_rfile);
 	if (err < 0) {
@@ -212,8 +212,7 @@ static int midisynth_use(void *private_data, struct snd_seq_port_subscribe *info
 	struct snd_rawmidi_params params;
 
 	/* open midi port */
-	err = snd_rawmidi_kernel_open(msynth->card, msynth->device,
-				      msynth->subdevice,
+	err = snd_rawmidi_kernel_open(msynth->rmidi, msynth->subdevice,
 				      SNDRV_RAWMIDI_LFLG_OUTPUT,
 				      &msynth->output_rfile);
 	if (err < 0) {
@@ -328,6 +327,7 @@ snd_seq_midisynth_probe(struct device *_dev)
 
 	for (p = 0; p < ports; p++) {
 		ms = &msynth[p];
+		ms->rmidi = rmidi;
 
 		if (snd_seq_midisynth_new(ms, card, device, p) < 0)
 			goto __nomem;